Neuropathic pain is a form of chronic pain and can be classified as peripheral or central. Peripheral neuropathic pain is caused by injury or infection of peripheral sensory nerves, whereas central neuropathic pain is caused by damage to the CNS or/and the spinal cord. Both peripheral and central neuropathic pain can occur without obvious initial nerve damage. The clinical causes of neuropathic pain are widespread and include both trauma and disease. Various metabolic diseases may be the cause of neuropathic changes and may subsequently be implicated in neuropathic pain. An example of such a neuropathy is diabetic neuropathy, which occurs in a large number of patients suffering from diabetes and may be associated with a large number of clinical symptoms such as a feeling of numbness, tingling sensation, or pain. Neuropathic pain may also result from cancer, either from nerve damage directly caused by the cancer (e.g., compression by a tumor), or as a side effect of chemotherapy, radiation or surgery.